Spotted fever

A spotted fever is a type of tick-borne disease which presents on the skin.[1] They are all caused by bacteria of the genusRickettsia. Typhus is a group of similar diseases also caused by Rickettsia bacteria, but spotted fevers and typhus are different clinical entities.

The phrase apparently originated in Spain in the seventeenth century and was ‘loosely applied in England to typhus or any fever involving petechial eruptions.’ During the seventeenth and eighteenth centuries, it was thought to be ‘“cousin-germane” to and herald of the bubonic plague’, a disease which periodically afflicted the city of London and its environs during the sixteenth and seventeenth centuries, most notably during the Great Plague of 1665.[2]

1.
Bacteria
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Bacteria constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods, Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only half of the bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology, There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are approximately 5×1030 bacteria on Earth, forming a biomass which exceeds that of all plants, Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of bodies and bacteria are responsible for the putrefaction stage in this process. In March 2013, data reported by researchers in October 2012, was published and it was suggested that bacteria thrive in the Mariana Trench, which with a depth of up to 11 kilometres is the deepest known part of the oceans. Other researchers reported related studies that microbes thrive inside rocks up to 580 metres below the sea floor under 2.6 kilometres of ocean off the coast of the northwestern United States. According to one of the researchers, You can find microbes everywhere—theyre extremely adaptable to conditions, the vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial particularly in the gut flora. However several species of bacteria are pathogenic and cause diseases, including cholera, syphilis, anthrax, leprosy. The most common fatal diseases are respiratory infections, with tuberculosis alone killing about 2 million people per year. In developed countries, antibiotics are used to treat infections and are also used in farming, making antibiotic resistance a growing problem. Once regarded as constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and these evolutionary domains are called Bacteria and Archaea. The ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, for about 3 billion years, most organisms were microscopic, and bacteria and archaea were the dominant forms of life. In 2008, fossils of macroorganisms were discovered and named as the Francevillian biota, however, gene sequences can be used to reconstruct the bacterial phylogeny, and these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage. Bacteria were also involved in the second great evolutionary divergence, that of the archaea, here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves possibly related to the Archaea

2.
Great Plague of London
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The Great Plague, lasting from 1665 to 1666, was the last major epidemic of the bubonic plague to occur in England. The Great Plague killed an estimated 100,000 people - almost a quarter of Londons population - in 18 months, the plague was caused by the Yersinia pestis bacterium, which is usually transmitted through the bite of an infected rat flea. As in other European cities of the period, the plague was endemic in 17th century London, the disease periodically erupted into massive epidemics. There were 30,000 deaths due to the plague in 1603,35,000 in 1625, during the winter of 1664, a bright comet was to be seen in the sky and the people of London were fearful, wondering what evil event it portended. London at that time consisted of a city of about 448 acres surrounded by a city wall, there were gates at Ludgate, Newgate, Aldersgate, Cripplegate, Moorgate and Bishopsgate and to the south lay the River Thames and London Bridge. In the poorer parts of the city, hygiene was impossible to maintain in the tenements and garrets. There was no sanitation, and open drains flowed along the centre of winding streets, the cobbles were slippery with animal dung, rubbish and the slops thrown out of the houses, muddy and buzzing with flies in summer and awash with sewage in winter. The City Corporation employed rakers to remove the worst of the filth, the stench was overwhelming and people walked around with handkerchiefs or nosegays pressed against their nostrils. Some of the necessities such as coal arrived by barge. Carts, carriages, horses and pedestrians were crowded together and the gateways in the wall formed bottlenecks through which it was difficult to progress, the nineteen-arch London Bridge was even more congested. The better-off used hackney carriages and sedan chairs to get to their destinations without getting filthy, the poor walked, and might be splashed by the wheeled vehicles and drenched by slops being thrown out and water falling from the overhanging roofs. Another hazard was the black smoke belching forth from factories which made soap, from breweries and iron smelters. Outside the city walls, suburbs had sprung up providing homes for the craftsmen and these were shanty towns with wooden shacks and no sanitation. The government had tried to control this development but had failed, other immigrants had taken over fine town houses, vacated by Royalists who had fled the country during the Commonwealth, converting them into tenements with different families in every room. These properties were soon vandalised and became rat-infested slums, administration of the City of London was organised by the Lord Mayor, Aldermen and common councillors, but not all of the inhabited area generally comprising London was legally part of the City. Both inside the City and outside its boundaries there were also Liberties, Westminster was an independent town with its own liberties, although it was joined to London by urban development. The Tower of London was an independent liberty, as were others, areas north of the river not part of one of these administrations came under the authority of the county of Middlesex, and south of the river under Surrey. At that time, bubonic plague was a much feared disease and it was not until 1894 that the identification by Alexandre Yersin of its causal agent Yersinia pestis was made and the transmission of the bacterium by rat fleas became known

3.
Mite
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Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology, in soil ecosystems, mites are favored by high organic matter content and by moist conditions, wherein they actively engage in the fragmentation and mixing of organic matter. Mites are among the most diverse and successful of all the invertebrate groups and they have exploited an incredible array of habitats, and because of their small size, go largely unnoticed. Many live freely in the soil or water, but there are also a number of species that live as parasites on plants, animals. It is estimated that 48,200 species of mites have been described, mites occupy a wide range of ecological niches. For example, Oribatida mites are important decomposers and occur in many habitats and they eat a wide variety of material including living and dead plant and fungal material, lichens and carrion, some are even predatory, though no species of Oribatida mite are parasites. Many mites which have well studied are parasitic on plants. One family of mites Pyroglyphidae, or nest mites, live primarily in the nests of birds and these mites are largely parasitic and consume blood, skin and keratin. Dust mites, which feed mostly on dead skin and hair shed from humans instead of consuming them from the organism directly, insects may also be infested by parasitic mites. Examples are Varroa destructor, which attaches to the body of the bee, and Acarapis woodi. There are hundreds of species of associated with other bee species. They attach to the bees in a variety of ways, for example, Trigona corvina workers have been found with mites attached to the outer face of their hind tibiae. Some are thought to be parasites, while others are beneficial symbionts, mites also parasitize some ant species, such as Eciton burchellii. Some of the plant pests include the spider mites, thread-footed mites. Among the species that attack animals are members of the sarcoptic mange mites, demodex mites are parasites that live in or near the hair follicles of mammals, including humans. Acari are mites, except for the three families of ticks, mites also hold the record speed, for its length, Paratarsotomus macropalpis is the fastest animal on Earth. The majority of species are harmless to humans, but a few species of mites can colonize humans directly, act as vectors for disease transmission. Mites which colonize human skin are the cause of several types of skin rashes, such as grain itch, grocers itch

4.
Flea
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Fleas are small flightless insects that form the order Siphonaptera. As external parasites of mammals and birds, they live by consuming the blood of their hosts, adults are up to about 3 mm long and usually brown. Bodies flattened sideways enable them to move through their hosts fur or feathers and they lack wings, and have mouthparts adapted for piercing skin and sucking blood and hind legs adapted for jumping. The latter enable them to leap a distance of some 50 times their body length, larvae are worm-like with no limbs, they have chewing mouthparts and feed on organic debris. Over 2,500 species of fleas have been described worldwide, the Siphonaptera are most closely related to the snow scorpionflies, placing them within the endopterygote insect order Mecoptera. Fleas arose in the early Cretaceous, most likely as ectoparasites of mammals and marsupials, each species of flea is more or less a specialist on its host animal species, many species never breed on any other host, though some are less selective. The oriental rat flea, Xenopsylla cheopis, is a vector of Yersinia pestis, the disease was spread by rodents such as the black rat, which were bitten by fleas that then infected humans. Major outbreaks included the Plague of Justinian and the Black Death, both of which killed a sizeable fraction of the worlds population. Fleas appear in human culture in such forms as flea circuses, poems like John Donnes erotic The Flea, works of music such as by Modest Mussorgsky. Flea legs end in strong claws that are designed to grasp a host, unlike other insects, fleas do not possess compound eyes but instead only have simple eyespots with a single biconvex lens, some species lack eyes altogether. Their bodies are compressed, permitting easy movement through the hairs or feathers on the hosts body. The flea body is covered with hard plates called sclerites and these sclerites are covered with many hairs and short spines directed backward, which also assist its movements on the host. The tough body is able to withstand great pressure, likely an adaptation to survive attempts to eliminate them by scratching, fleas lay tiny, white, oval eggs. The larvae are small and pale, have bristles covering their bodies, lack eyes. The larvae feed on organic matter, especially the feces of mature fleas, adults feed only on fresh blood. Immediately before the jump, muscles contract and deform the resilin pad, to prevent premature release of energy or motions of the leg, the flea employs a catch mechanism. Early in the jump, the tendon of the primary jumping muscle passes slightly behind the coxa-trochanter joint, generating a torque which holds the joint closed with the leg close to the body. To trigger jumping, another muscle pulls the tendon forward until it passes the joint axis, generating the opposite torque to extend the leg, the actual take off has been shown by high-speed video to be from the tibiae and tarsi rather than from the trochantera

5.
Rickettsia rickettsii
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Rickettsia rickettsii is a gram-negative, intracellular, coccobacillus bacterium that is around 0.8 to 2.0 micrometers long. R. rickettsi is the agent of Rocky Mountain spotted fever. R. rickettsii is one of the most pathogenic Rickettsia strains known to humans and affects a large majority of the Western Hemisphere, Rocky Mountain spotted fever first emerged in the Idaho Valley in 1896. At that time, not much information was known about the disease, the first clinical description of Rocky Mountain Spotted Fever was reported in 1899 by Edward E. Maxey. Howard Ricketts, a professor of pathology at the University of Chicago in 1902, was the first to identify. At this time, the trademark rash now began to emerge in the western Montana area. His research entailed interviewing victims of the disease and collecting and studying infected animals and he was also known to inject himself with pathogens to measure their effects. Unfortunately, his research was cut short after his death from an insect bite. S. Burt Wolbach is credited for the first detailed description of the agent that causes R. rickettsii in 1919. He clearly recognized it as a bacterium which was seen most frequently in endothelial cells. The most common hosts for the R. rickettsii bacteria are ticks, ticks that carry R. rickettsia fall into the family of Ixodidae ticks, also known as hard bodied ticks. Ticks are vectors, reservoirs and amplifiers of this disease, there are currently three known tick specifics that commonly carry R. rickettsii. American dog tick Rocky Mountain Wood Tick Brown dog tick, ticks can contract R. rickettsii by many means. Once a tick becomes infected with this pathogen, they are infected for life, in addition, an infected male tick can transmit the organism to an uninfected female during mating. Once infected, the tick can transmit the infection to her offspring. Due to its confinement in the midgut and small intestine, Rickettsia rickettsii can be transmitted to mammals, transmission to mammals can occur in multiple ways. One way of contraction is through the contact of infected host feces to an uninfected host, if infected host feces comes into contact with an open skin wound, it is possible for the disease to be transmitted. Additionally, an uninfected host can become infected with R. rickettsii when eating food that contains the feces of the infected vector, another way of contraction is by the bite of an infected tick

6.
Anaplasma phagocytophilum
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Anaplasma phagocytophilum is a gram-negative bacterium that is unusual in its tropism to neutrophils. It causes anaplasmosis in sheep and cattle, also known as fever and pasture fever. Anaplasma phagocytophilum is a Gram-negative, obligate bacterium of neutrophils and it causes human granulocytic anaplasmosis, which is a tick-borne rickettsial disease. Because this bacterium invades neutrophils, it has a unique adaptation, anaplasma phagocytophilum is a small, obligate, intracellular bacterium with a Gram-negative cell wall. It is 0. 2–1.0 μm and lacks a lipopolysaccharide biosynthetic machinery, the bacterium first resides in an early endosome, where it acquires nutrients for binary fission and grows into small groups called morulae. This bacterium prefers to grow within myeloid or granulocytic cells, anaplasma phagocytophilum causes human granulocytic anaplasmosis. This disease was first identified in 1990, although this pathogen was known to cause veterinary disease since 1932, since 1990, incidence of this disease has increased, and it is now recognized in Europe. This disease was first identified due to a Wisconsin patient who died with a severe illness two weeks after a tick bite. During the last stage of the infection, a group of bacteria were seen within the neutrophils in the blood. Other symptoms include fever, headache, absence of skin rash, leucopenia, thrombocytopenia, the disease is multisystemic, but the most severe changes are anaemia and leukopenia. This organism causes lameness which can be confused with symptoms of Lyme disease and it is a vector borne zoonotic disease whose morula can be visualized within neutrophils from the peripheral blood and synovial fluid. It can cause lethargy, ataxia, loss of appetite, anaplasma phagocytophilum binds to fucosylated and sialylated scaffold proteins on neutrophil and granulocyte surfaces. A type IV secretion apparatus is known to help in the transfer of molecules between the bacterium and the host, the most studied ligand is PSGL-1. The bacterium adheres to PSGL-1 through 44-kDa major surface protein-2, after the bacterium enters the cell, the endosome stops maturation and does not accumulate markers of late endosomes or phagolysosomes. Because of this, the vacuole does not become acidified or fused to lysosomes, a. phagocytophilum then divides until cell lysis or when the bacteria leave to infect other cells. This bacterium has the ability to affect neutrophils by altering the function of the host cell and it can survive the first encounter with the host cell by detoxifying superoxide produced by neutrophil phagocyte oxidase assembly. It also disrupts normal neutrophil function, such as cell adhesion, transmigration, motility, degranulation, respiratory burst. It causes an increase in the secretion of IL-8, a chemoattractant that increases the phagocytosis of neutrophils, the purpose of this is to increase bacterial dissemination into the neutrophil

7.
Orientia tsutsugamushi
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Orientia tsutsugamushi is the causative organism of scrub typhus, and the natural vector and reservoir is probably trombiculid mites. The organism is an intracellular pathogen, which needs to infect eukaryotic cells in order to multiply. The envelope is similar to that of Gram negative bacteria, but it is not easily stained with Gram stain, genetic methods have revealed even greater complexity than had been previously described. Infection with one serotype does not confer immunity to other serotypes, repeated infection in the same individual is therefore possible, and this complicates vaccine design. The bacterium was initially categorised in the genus Rickettsia, but is now classed in a genus, Orientia. It is 0.5 µm wide and 1.2 to 3.0 µm long, the organism is highly virulent and should only be handled in a laboratory with biosafety level 3 facilities. O. tsutsugamushi is sensitive in vitro to doxycycline, rifampicin and azithromycin and it is innately resistant to all β-lactam antibiotics because it lacks a classical peptidoglycan cell wall. Aminoglycosides are also ineffective in human infection because the organism is intracellular, there are currently no licensed scrub typhus vaccines available. It is now known there is enormous antigenic variation in Orientia tsutsugamushi strains. Any scrub typhus vaccine should give protection to all the strains present locally, a vaccine developed for one locality may not be protective in another locality, because of antigenic variation. This complexity continues to hamper efforts to produce a viable vaccine

8.
Genus
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A genus is a taxonomic rank used in the biological classification of living and fossil organisms in biology. In the hierarchy of classification, genus comes above species. In binomial nomenclature, the name forms the first part of the binomial species name for each species within the genus. Felis catus and Felis silvestris are two species within the genus Felis, Felis is a genus within the family Felidae. The composition of a genus is determined by a taxonomist, the standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. Moreover, genera should be composed of units of the same kind as other genera. The term comes from the Latin genus, a noun form cognate with gignere, linnaeus popularized its use in his 1753 Species Plantarum, but the French botanist Joseph Pitton de Tournefort is considered the founder of the modern concept of genera. The scientific name of a genus may be called the name or generic epithet. It plays a role in binomial nomenclature, the system of naming organisms. The rules for the names of organisms are laid down in the Nomenclature Codes. The standard way of scientifically describing species and other lower-ranked taxa is by binomial nomenclature, the generic name forms its first half. For example, the gray wolfs binomial name is Canis lupus, with Canis being the name shared by the wolfs close relatives. The specific name is written in lower-case and may be followed by names in zoology or a variety of infraspecific names in botany. Especially with these names, when the generic name is known from context. Because animals are typically only grouped within subspecies, it is written as a trinomen with a third name. Dog breeds, meanwhile, are not scientifically distinguished, there are several divisions of plant species and therefore their infraspecific names generally include contractions explaining the relation. For example, the genus Hibiscus includes hundreds of other species apart from the Rose of Sharon or common garden hibiscus, Rose of Sharon doesnt have subspecies but has cultivars that carry desired traits, such as the bright white H. syriaca Diana. Hawaiian hibiscus, meanwhile, includes several separate species, since not all botanists agree on the divisions or names between species, it is common to specify the source of the name using author abbreviations

9.
Alphaproteobacteria
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Alphaproteobacteria is a class of bacteria in the phylum Proteobacteria. Its members are diverse and possess few commonalities, but nevertheless share a common ancestor. Like all Proteobacteria, its members are Gram-negative and some of its intracellular parasitic members lack peptidoglycan and are consequently gram variable. Moreover, the class includes the protomitochondrion, the bacterium that was engulfed by the ancestor and gave rise to the mitochondria. A species of technological interest is Rhizobium radiobacter, scientists use this species to transfer foreign DNA into plant genomes. There is some disagreement on the phylogeny of the orders, especially for the location of the Pelagibacterales and this issue stems form the large difference in gene content and the large difference in GC-richness between members of several order. Specifically, Pelagibacterales, Rickettsiales and Holosporales contains species with AT-rich genomes and it has been argued that it could be a case of convergent evolution that would result in an artefactual clustering. The basal group is Magnetococcidae, which is composed by a diversity of magnetotactic bacteria. The Rickettsidae is composed of the intracellular Rickettsiales and the free-living Pelagibacterales, the Caulobacteridae is composed of the Holosporales, Rhodospirillales, Sphingomonadales, Rhodobacterales, Caulobacterales, Kiloniellales, Kordiimonadales, Parvularculales and Sneathiellales. These molecular signatures provide novel means for the circumscription of these taxonomic groups, alphaproteobacteria at the US National Library of Medicine Medical Subject Headings Bacterial Phylogeny Webpage, Alpha Proteobacteria

Infected Oriental rat flea. Yersinia pestis bacteria appear as a dark mass in the gut. The bacteria block the flea's digestive system, leaving it hungry but unable to eat. Instead, when it tries to feed, it regurgitates Yersinia into the wound.